Dual-Mechanism Gas Flow Dynamics in Single- and Dual-Porosity Systems

Unconventional natural gas has been defined as pipeline quality (high BTU-content) gas produced from geologic formations that have not been exploited by the oil and gas industry due to the cost and difficulty of producing the gas. These unconventional gas resources include tight sands, geopressured aquifers, Devonian shales, and coal seams. These unconventional gas reservoirs arc characterized by low permeability and porosity characteristics which make it difficult for the gas to flow through the geologic formations towards the well. Furthermore, presence of extensive natural fracture networks, soiption phenomena, and dispersed gas bubbles complicate the performance analysis of these reservoirs because phenomenologically more complicated mechanisms control the flow dynamics.